This hypertensive disorder of pregnancy is defined as a new onset of hypertension and proteinuria after 20 weeks of gestation. In Australia, we don't need proteinuria; we are happy to make the diagnosis with any sort of organ dysfunction. The definition of eclampsia is the presence of otherwise unexplainable seizures in a patient with preeclampsia.

This comes up fairly frequently in the SAQs. In broader terms, the pregnancy-related SAQs which are not about the jaundiced comatose woman are usually about the hypertensive seizure lady. These two variants between them seem to cover about 75% of the total spectrum of past paper questions. So, knowing these topics well sets you up to pass the majority of O&G material in the Part II exam. Here is a list of previous preeclampsia related questions:

Of these, several are not specifically about preeclampsia. Rather, it is the most sensible differential from a list of differentials which the candidates are expected to generate. For instance, Question 19 from the second paper of 2014 offers a scenario where a medically complex pregnant patient presents in such a manner as to bring up serotonin syndrome and PRES as sensible differentials, and preeclampsia is merely one of the possibilities.

Others have held forth extensively on the pathogenesis of this condition; suffice to say it is thought to be a systemic response to placental hypoperfusion, with increased activation of the potent vasoconstrictor endothelin-1, as well as an increased sensitivity to vasoconstrictors in general, and a down-regulation of vasodilatory mechanisms such as nitric oxide synthase.

Diagnostic features

In order to be labelled as a pregnant woman with preeclampsia, one must have a certain set f features:

Diagnostic criteria for preeclampsia:

Hypertension: 140/90 mmHg

Proteinuria: Over 0.3g of protein in a 24 hr collection;

a random urine protein./creatinine ratio over 30mg/mmol

Furthermore, there are several features which suggest that the condition is severe, and worth worrying about:

Features of severe preeclampsia:

Severe Hypertension: 160/110 mmHg

Intracranial haemorrhage or stroke can occur

Cardiovascular collapse:

Normal contractility but massively increased afterload

This progresses to pulmonary oedema

Massive Proteinuria: Over 2g of protein in a 24 hr collection;

Renal failure with oliguria

Uric acid levels may rise

Deranged LFTs

There may be hepatic oedema and rupture

Visual disturbance, clonus, headaches

this progresses to seizures, cerebral oedema and stroke

There may be a posterior reversible encephalopathy

Thrombocytopenia, DIC, haemolysis

Investigations

A standard panel of tests should be requested:

FBC

EUC

LFT

Coags

Uric acid levels

Urinalysis

Continuous ECG monitoring of the mother, and continuous foetal heart monitoring should commence.

Workup of the non-specific preeclampsia-like presentation in the pregnant patient

Question 19 from the second paper of 2014 presented a scenario with numerous possible causes for fever and decreased level of consciousness; the question from the college was mainly about generating differentials and doing a diagnostic workup. The list of differentials was enormous, made more so by the following features of the presenting history:

Management of preeclampsia

The key step is to get the baby out. Everything returns to normal after delivery. Except pulmonary oedema: this may actually be exacerbated.

While you are organising the delivery, there are various supportive measures which should be taken:

Blood pressure control

On one hand, one must prevent maternal stroke, intracranial haemorrhage and cerebral oedema. On the other hand, one must perfuse the placenta. The key is to keep the systolic under 160, and the diastolic under 110.

Labetalol, hydralazine and nifedipine are used as first line agents. There is no difference between them in terms of outcomes.

Methyldopa and sodium nitroprusside are second-line agents, if the hypertension is refractory.

Anticonvulsants

Magnesium sulfate is the primary agent. Both Oh's manual and the RCOG statement quote the MAGPIE study, which convincingly demonstrated a reduction in maternal morbidity with magnesium. How it works, nobody knows. It has a half-life of 4 hours and is rapidly excreted (its pharmacokentics are dealt with elsewhere). One aims for a serum level of 2.0-3.5mmol/L.

Respiratory paralysis is difficult to accomplish; you need a level over 7.5mmol/L. As long as the deep tendon reflexes are present, you are unlikely to develop that sort of toxicity.

Seizure control in eclampsia

Give an extra dose of magnesium

Administer IV diazepam

Consider phenytoin

If all else fails, its time for thiopentone and intubation.

In general, there might be many possible aetiologies for the seizures, and one must consider a CT head to exclude major structural pathology.

A template approach

Attention to the ABCS, with management of life-threatening problems simultanous with a rapid focused examination and a brief history.

Airway:

Assess the need for airway support in context of post-ictal unconscious state

Weigh benefits of intubation against risks in context of the known airway access problems associated with pregnancy

Breathing/ventilation

Assess oxygenation and briefly examine for aspiration

High flow oxygen via NRBM if patient is not in need of immediate intubation

Circulatory support

Assess cardiovascular stability

left lateral 30° tilt if hypotensive

Access with widebore cannula

Immediate investigations:

FBC - looking for thrombocytopenia

LFTs - looking for HELLP, hepatic encephalopathy

EUC - looking for hyponatremia

CMP

Coags

Antiepileptic drug levels, if relevant

CT brain, if the patient fails to awaken

Specific management

Antihypertensives:

labetalol, nifedipine or hydralazine are of equivalent benefit

methyldopa and sodium nitroprusside are second line agents

Antiepileptic therapy:

Loading dose of magnesium sulfate, followed by an infusion, aiming at a serum level of 2.0-3.5mmol/L

Diazepam and phenytoin can be considered if seziures are refractory

Arrange for a consultation with the obstetrician regarding the safety and practicality of immediate delivery.